Protecting microchip technology deployed in the field is an enormous concern in both military and commercial sectors. Microchips and related devices are routinely acquired by motivated competitors and governments seeking to reverse engineer or otherwise learn the functionality of the technology. Such information is used to make a technological leap in their own devices, or may be used to exploit a perceived weakness in the examined equipment. Sophisticated government and commercial entities thus possess ample strategic and economic motivation to reverse engineer microchip components.
A microchip, or integrated circuit, is a unit of packaged computer circuitry that is manufactured from a material, such as silicon, at a very small scale. Microchips are made for program logic (logic or microprocessors) and for computer memory (Random Access Memory or other memory microchips). Microchips are also made that include both logic and memory, and for special purposes, such as analog-to-digital conversion, bit slicing and gateways.
An advanced method of reverse engineering select microchip components uses high energy photons, electrons or ions. Focused ion beam processes excite active portions of a microchip to observe how other portions are affected. When used to reverse engineer, these processes are typically done while the microchip is in a powered-on state in order to observe the functionality of the microchip.
Microchip designers in the aerospace, defense and commercial industries routinely implement software and other logic-related techniques to confuse and thwart attempts to probe the active side of the component. For example, safeguard measures integrated within microchips hinder reverse engineering techniques. Microchip designers capitalize on the powered on status required by a reverse engineering process to incorporate a self-destruct or obstructing mechanism into the microchip. The mechanism is triggered by the detection of tampering. When tampering is detected, the power in the circuit is diverted to microchip annihilation or another predetermined measure.
Microchip designers sometimes impede the reverse engineering processes by plating the back of the bulk silicon with a metal layer. While intact, this layer obstructs both the insertion of ions and electrons, and the observation of photons. Using multiple assembly processes, mesh sensors may be placed around security sensitive circuitry.
While these safeguards provide some protection, motivated exploiters have developed ingenious ways of analyzing the microchip without triggering the safeguard mechanisms. Despite the precautions, the backside of the microchip remains vulnerable to inspection by photons, focused ion beam, or even simple infrared observation. Sophisticated exploitation techniques overcome conventional obstacles by removing the bulk silicon and metallized back layer. For instance, reverse engineering processes may grind away the metallized portion towards implementing a successful focused ion beam operation. In this manner, microchip information may be exploited in a manner that does not initialize a self-destruct feature.